Two-way damper with adjustable sensitivity

Claim 1

A TWO-WAY ACTIVE DAMPER COMPRISING A DAMPER BLADE ADAPTED TO BE MOUNTED IN AN UPRIGHT SLEEVE SECTION, A ROCKER SHAFT PIVOTALLY SUPPORTING THE DAMPER BLADE IN THE BORE OF THE SLEEVE SECTION FOR TILTING MOVEMENT ON AN AXIS WHICH IS OFFSET FROM THE GEOMETRICAL CENTER OF THE DAMPER BLADE, ADJUSTABLE COUNTERBALANCING MEANS ON THE DAMPER BLADE TO PERMIT THE DAMPER BLADE TO ASSUME A LEVEL BORE CLOSING POSITION, SAID DAMPER BLADE HAVING A RADIAL SLOT FORMED THERETHROUGH, AN ADJUSTING SLIDE PLATE ON ONE FACE OF THE DAMPER BLADE AND HAVING AN ADJUSTING SLOT LENGTHWISE OF THE FIRST-NAMED SLOT AND AT RIGHT ANGLES TO SAID AXIS, MEANS TO CLAMP THE SLIDE PLATE IN A SELECTED ADJUSTED POSITION UPON THE DAMPER BLADE, AND A RETRACTILE SPRING ADJACENT THE FIRST-NAMED SLOT AND ADAPTED TO PASS THROUGH THE SLOT WHENEVER THE DAMPER BLADE TILTS IN EITHER DIRECTION UPON SAID AXIS, SAID SPRING HAVING ONE END SECURED TO SAID SLIDE PLATE AND ITS OPPOSITE END SECURED TO THE SLEEVE SECTION, SAID SPRING, DAMPER BLADE AND SLIDE PLATE ALL LYING SUBSTANTIALLY, IN A COMMON PLANE WHEN THE DAMPER BLADE IS IN THE LEVEL BORE CLOSING POSITION.